The invention relates to an end fitting tensioner for seat belt systems in vehicles.
Belt tensioners for seat belt systems are generally known already from automotive engineering. In so-called end fitting tensioners in the case of activation of the belt tensioner the actually fixed end of a webbing usually connected to the seat frame or the vehicle body is tightened in order to provide for tensioning of the entire webbing. In the state of the art both linearly operating as well as rotatory end fitting tensioners are described. In the rotatory end fitting tensioners the webbing end is connected to a belt shaft which is driven upon activation of the belt tensioner so as to wind webbing onto the belt shaft.
For driving the belt shaft in the tensioning direction, usually a gas generator is provided for generating a gas pressure after being triggered and thus displacing a piston in a cylindrical tensioner tube along the tube axis. The piston is connected to the belt shaft by a pull rope, for instance, so that the belt shaft is driven in the tensioning direction and belt webbing is wound onto the belt shaft. In the initial state the pull rope is fastened by one rope end to the piston and by an opposite rope end to a rope reel connected to the belt shaft in a rotationally fixed manner and is partly wound onto the rope reel. After activation of the rotatory end fitting tensioner, pull rope is unwound from the rope reel, while the belt shaft rotates, and simultaneously webbing is wound onto the belt shaft so that belt tensioning takes place.